Originally Posted by Bandit
We have a new to us Conquest B Touring RV. The area in front of the fridge, going into the bedroom is a bit spongy. I can feel braces where it is solid but then spongy in-between. Trying to find out what the construction is under the linoleum flooring and what can I expect to get it fixed.
Under the lino you will find:
3/4" OSB that has turned to mush
A thin layer of fiberglass insulation
A steel frame work to support the floor
A thick black vapour barrier / weather protection. You can see this inside the top of your bins.
The mushy OSB has to be removed. Tke it back to the steel supports. Replace it with 3/4" 5 or 7 ply marine grade plywood. 7 ply is preferable. You can just attach the plywood direct to the steel framework with screws. Check to make sure it is steel frame work. If aluminum you do not want to use steel screws in the aluminum.
if you can see under the fridge you will probably find out it is spongy as well. If that's the case you can either forget about fixing it, or taking the fridge out and replacing the OSB or cantilever some of the plywood under there.
Once that is done you can get floor levelling material from Home Depot or Lowes to level out the joints. Don't get the water based one. There is one make out there that is a paste you just smooth on and sand down.
This is from my experience with spongy floors.